SOTLS
1136 Journal of Medicinal Chemistry, 1971, Vol. 14, N o . 11
(IV), and would thus be expected to “fit” the active site better than those compds which do not have the
Iv
0 0
b, -0.30
-0.20
0.10
,
-0 00
N e t Charge on Nitrogen, QN
Figure 1.-Butyrylcholinesterase inhibition of some 3-substituted-1-decylpiperidines us. net charge on the N of the substituent group. (Data points included are those for the compds for which K , values have been determined, z.e., 1-5, Table 11.)
were done on the nonprotonated species, however, to see if protonation of the piperidine nitrogen was “felt” by the substituent atoms a t the 3 position of the piperidine ring. Using parameter values for a protonated piperidine nitrogen instead of a tertiary S did not change the charge densities on the atoms attached a t the 3 position. An explanation that has been proposed by Bergmann, et al., for the cholinesterase inhibition of compds containing the RCO function is “that the inhibition is related to the effect of the substituting (R) group upon the electrophilic character of the carbonyl carbon.” l o With this in mind one would expect that an increase in the activity of the compds of series I, 11, and I11 (1-5, Table 11) would be reflected in an increase in the positive value for the net charge on the carbonyl C. This does not seem to be the case, however, as can be seen in Table 11. Although the most active compd does have the most positive value as anticipated, the least active compds do not have the smallest positive charge on the carbonyl C. Thus, it would seem that while the electrophilic character of the carbonyl C is important for BuChE inhibition as illustrated by thp most active compd (2, Table 11), its contribution to BuChE inhibition is modified by the alkyl groups of the carboxamide function as seen in 3, 4, and 5. If one examines the total charge on the carbonyl 0, Qo, of 1-5 in Table 11, it can be seen that the most active compd has the greatest negative charge. The total charge on the carbonyl 0 for the other compds has such small variation, hou-ever, that no conclusion can be drawn concerning a relationship between the total charge on the carbonyl 0 and activity. Purcell has reported that, for a series of 1-decy1-3[(N-alkyl)- and 1-decyl-3-[ (N,N-dialky1)substituted carbamoyl ]piperidines, the BuChE inhibitory activity increased a8 the amide N became more positive.” The activity for the acetamide, urea, and substituted amides (1-5, Table 11) increases as the r\’ in the respective moieties (dimethyl-substituted 9 for 2) becomes more positive (Figure 1 ) . It is interesting to note that, whereas a part of the acetamide V shown by darker bonds is isosteric with the choline ester, acetylcholine (10) F. Herpmann, I I3 Wilson and D Nachmansohn, J 186,693 (1950) (11) W.P. Purcell J. Med Chem , 9 , 294 (1966)
Bzol Chem
0
H
V
ACh “backbone,” it is less active than 2 of the carboxamide compds (3 and 5, Table 11) in which the number of atoms separating the cationic S and the CO group is less than in the choline esters. This points out the dynamic nature of the interaction of inhibitor and enzyme; factors other than the proper positioning of certain atoms which are believed to be :ictive-aitt>directing centers must also be of v i t d importntict.. ,2lso, it is the charge density on t h e dimcth? 1-substituted K of 2 that seems to correlate nith activit;\ (Figure 1); this S is situated differently t h a i t cithcr the K of the acetamide or the carboxaniidcs. Th:ri the charge density on the differently situated ( ? . e . regarding the number of bonds b e t w e n the K and the pii)c1idiriium 1)nitrogens is related t o activity indicates that electronic charge densities ma! affect the m a ~ i n ~11ir n-hich the enzyme and inhibitor molecules fit together so that the piperidinium nitrogens and the nitrogelis examined in Table I1 have similar distances bctn een them. ,1 comparison nas made of BuChE inhibitor! iictivities and amide K charge densities for the series of carboxamide derivatives (3-9, Tablc 11) in :in iittempt to delineate further the role of electrostatic charges in BuChE inhibition. Calcris show that there 15 w r y little variation in the charge distribution of t h r C’OXH, function while there is considerable variation in thrl BuChE inhibitory potencies, thus serving to illustrate that the hydrophobic character of thc alkyl g r o u p on the CONH, function is the controlling factor in thc BuChE inhibition of these compds. These result\ are in agreement with those of I’urcell, t t al., \Tho attributc a major part of the activity of 3-9. Table 11, to re1:1t Ivt’ ’ hydrophobicities of the molecules.?”
Acknowledgment. -The author< uibh to thaiik 1 1 1 h n 1IcEachran and A i m . .Julia Lntham of tht’ vercity of Terineqsee Computer Project for thcir a ancc in operating thc IBAI 16’20 computer a11d George E. B a s for hi\ a tunce i r i the citlculatlon~. Also, T\ e \ \ o d d 1 1 1 ~to c q r w our gratitudc t o 111. J. G. Beasley for permitting u s t o incluclc w n i ~of unpublished data in Table I1 :md for 111- helpful ~ ~ 0 1 1 1 ments (111 the nianu,cript.
Chemistry of Cephalosporin Antibiotics. 25. 3-Cyanomethyl Cephem Nucleus
Sumcrous structural manipulations have been c a r r i d out at thc 3 position of the cephem nucleus. J1odific.a-
Journal of Medicinal Chemistry, 1971, Vol. 14, No. 11 1137
NOTES
TABLE I ANTIBACTERIAL ACTIVITIES OF THIOPHENEACETYL DERIVATIVES QCH*COWS
0H>CH2XCOOH Resistant
I
X
S. aureus"
N-9
N-10
N-26
OAc
0.4
7.5
8.7
10.5
Gram-negativeb X-26
0.7
-7
X-68
K-1
X-528
3.0
4.1
>50
He 9.0 >50 >50 >50 6.4 >50 >50 >50 OCH3d 0.4 >50 39.0 38.0 43.4 12.4 22.1 >50 SCHa' 1.9 38.0 >50 16.8 18.3 >50 CN 2.4 30.0 22.5 27.0 5.2 8.8 8.1 >50 MIC in pg/ml by gradient plate assay. Each figure is the avg value obtained using 3 penicillin-resistant, coagulase-positive Staphylococcus aureus strains. b MIC in pg/ml by gradient plate assay: N-9 = Shigella sp.; N-10 = Escherichia coli; N-26 = E. coli; X-26 = Klebsiella pneumoniae; X-68 = Enterobacter aerogenes; K-1 = K . pneumoniae; X-528 = Pseudomonas sp. Ref 3; prepd by C. W. Ryan. d Ref 11. e Prepd by Dr. I. G. Wright, according to Belgian Patent 734,533 (1069). (1
tions of the naturally occurring 3-acetoxymethyl func7-phenoxyacetamido-2-cephem-4-carboxylate ester (2). tion have resulted in direct replacement of AcO by SI We feel that the unique success of Cuz(CN)z in DRISO in this Br- displacement results from an optimum comand Kznucleophiles, hydrogenolytic cleavage3t o a 3-Me promise of solubility, nucleophilicity, and basicity moiety, and indirect replacement by S,4 N , 4 a v 5 and O5dV6 moieties. which minimizes 0-lactam destruction but still allows There exist a few examples of cephalosporin derivathe desired displacement. tives in which the AcO group has been replaced by a C The 2-cephem derivative (2) was converted to its nucleophile. These were obtained via direct displace3-cephem isomer (3) by oxidation and reduction a t the ments by indole derivatives,'& resorcinol,1a and pyrS atom (see Experimental S e c t i ~ n ) . ~ , ~ . ' ~ roles4and indirect replacement by the enamine of cyclohexanone.6a PhOCH,CONH PhOCH,CONH We wish to report the preparation of a 3-cyanomethyl cephem nucleus, the formal result of replacement of CH,CN AcO by the C nucleophile, CN.6b I Starting material for our synthesis was the 3-bromoCO1-f(~/.t-Bu CO,-tert-Bu 1 2 methyl-2-cephem derivative ( l ) . 7 7 8 This allylic bromide undergoes acetate displacement7and also alcoholysis to give 3-alkoxymethyl cephem derivatives.8 Attempts to displace Br from 1 by CN-, ordinarily an excellent nucleophile, gave poor results using NaCN or KCN in numerous solvents; but the use of C U ~ ( C N ) ~ , often used to replace aromatic halogen^,^ in a dipolar aprotic medium led to successful displacement. The C0,-tert-Bu C0,-tert -Bu best solvent was DMSO. Chromatography of the 4 3 DMSO product provided crystalline 3-cyanomethyl-
1
I
(1) (a) J. D. Cocker, B. R . Cowley, J. S. G. Cox, S. Eardley, G. I. Gregory, J. K. Laaenby, A. G. Long, J. C. P. Sly, and G. A. Somerfield, J . Chem. Soc., 5015 (1965); (b) E. Van Heyningen and C. N. Brown, J . Med. Chem., 8, 174 (1965). (2) (a) C. W. Hale, G. G. F. Newton, and E . P. Abraham, Biochem. J . , 79, 403 (1961); (b) J. L. Spencer, F. Y. Siu, E . H. Flynn, B. G. Jackson, M. V. Sigal, H. M. Higgins, R. R. Chauvette, 8. L. Andrews, and D. E . Bloch, Antimicrob. Ag. Chemother., 573 (1966); (c) J. Bradshaw, S. Eardley, and A. G. Long, J . Chem. Soc. C , 801 (1968). (3) R . J. Stedman, K. Swered, and J. R . E . Hoover, J . M e d . Chem., 7 , 117 (1964). (4) (a) J. S. G. Cox, H. Fazakerley, and J. D. Cocker, U. S. Patent 3,278,531 (1966); (b) Glaxo Lab. Ltd., Belgium Patent 734,532 (1969), and Glaxo Lab. Ltd., Belgium Patent 734,533 (1969). ( 5 ) (a) E. P. Abraham, G. G. F. Newton, and C. W.Hale, U. S. Patent 3,226,384 (1965); (b) Glaxo Lab. Ltd., U. S. Patent 3,274,186 (1964); (c) Glaxo Lab. Ltd., Netherlands Patent 67,17107 (1968); (d) Glaxo Lab. Ltd., Belgium Patent 719,710 (1969). ( 6 ) (a) Glaxo Lab. Ltd.. Belgium Patent 719,711 (1969); (b) Eli Lilly, Netherlands Patent 69,02013 (1969). (7) J. .4. Webber, E. M. Van Heyningen, and R. T. Vasileff, J . Amer. Chem. Sac., 91, 5674 (1969). (8) J. A. Webber, G. W. Huffman, R . E. Koehler, C. F. Murphy, C. W. Ryan, E. M . Van Heyningen, and R. T. Vasileff, J . .Wed. Chem., 14, 113 (1971). (9) L. Friedman and H. Shechter, J . Org. Chem., 26, 2522 (1961).
R = iert-Bu b, R = H
Sa,
Phenoxyacetyl side chain cleavage" of 3, initiated by treatment with PC15, was performed successfully without extensive destruction of the CN moiety. Reacylation (10) G. V. Kaiser, R . D. G. Cooper, R . E. Koehler, C. F. Murphy, M. Van Heyningen, ibid., 36, 2430 (1970). (11) R . R. Chauvette, P. A. Pennington, C. W. Ryan, R . D. G . Cooper, F. L. Jose, I. G. Wright, E . M. Van Heyningen, and G. W. Huffman, J . Org. Chem., 36, 1259 (1971).
J. A. Webber, I. G. Wright, and E.
1138 Journal of Medicinal Chemistry, 1971, Vol. 14, N o . 1 1
of the resulting amino ester nucleus, isolated as the tosylate salt (4), with thiopheneacetyl chloride provided the 3-cyanomethyl-7-thiopheneacetamido cephem ester (5a). Much decomposition occurred during ester cleavage of 3 or 5a with acid. I n the case of 5a, however, some cephem acid material was isolated for antibacterial testing. The decomposition observed may result from carboxyl cyclization with the cyano moiety. The resulting iminolactone might then polymerize or otherwise lead to intractable material. Table I provides gradient plate in vitro antibacterial activities for 5b compared with other thiopheneacetamido cephem derivatives.
Experimental Section Melting points were detd using a Mel-Temp app and are uncor. Uv spectra were detd in EtOH, ir spectra in CHCls or as a mull. Nmr spect'ra were obtd using a Varian HA-60 spectrometer in CDCb, acetone-dfi, or DMSO-de. All cryst' compds were charact,erized by ir, uv, nmr, and elemental anal. (C, H, N ) . Unless otherwise stated, anal. were within +0.4% of the theor value. tert-Butyl 3-Cyanomethyl-7-phenoxyacetamido-2-cephem-4carboxylate (2).-To a stirred, cooled soln cont'g 5.0 g (-10 mmoles) of bromide 1, dissolved in 90 ml of DMSO and 30 ml of DMF, was added solid C U Z ( C N )(896 ~ mg, 10 mmoles). After being stirred with slow warming to 20" over 3 hr, 10 ml of cold 5% HC1 contg 4.0 g of FeC13 6H20 was added, and the mixt was stirred in the cold (0-5') for lt5 min. C6H6 and satd aq NaCl were added, and the sepd org layer was washed with satd aq NaC1, satd NaHC03, and satd NaCl and dried (MgSO4 with decolorizing charcoal). Filtn and evapn of the C& soln yielded 4.0 g of crude 2 which was purified by column chromatog on silica gel-1-57, HzO. Compd 2 was eluted by 4% EtOAc in C6Ho and crystd from Et20, mp 117-120". tert-Butyl 3-Cyanomethyl-7-phenoxyacetamido-3-cephem-4carboxylate (3).-To a stirred, cooled soln contg 1.3 g (3 mmoles) of 2 dissolved in 40 ml of CH2C12and 200 ml of i-PrOH was added dropwise 615 mg (3 mmoles) of m-ClC6H4C03H (85%) dissolved in 100 ml of i-PrOH and 100 ml of CHzC12. The mixt was stirred for 4 hr and allowed to warm slowly to room temp before being evapd to dryness. The residue was dissolved in 12 ml of 3 : l CH&N-DMF, and cooled in an ice bath before 1.3 g of SnCl2 (anhyd) and 5 ml of AcCl were added. After standing 50 min in the cold and 45 min a t room temp, the reaction mixt was evapd to dryness, anti then was dissolved in CeH6; this soln was washed with cold 5% HCI, satd NaHC03, and satd NaCl, then dried (RlgS04), and evapd to give 1.7 g of crude 3 as an oil that was purified by column chromatog. The desired material, eluted by 4-80/: EtOAc in C6H6,did not crystallize, but was characterized by spectral data. tert-Butyl 7-Amino-3-cyanomethyl-3-cephem-4-carboxylate Tosylate (4).-To a stirred soln contg 429 mg (1 mmole) of 3 diasolved i n 20 ml of dry C6H6was added 118 mg (1.5 equiv) of dry pyridine in 5 ml of dry C&; immediately following, 132 mg (1.,3 equiv) of PCle was added. -4fter heating a t 57" for 2 hr, the reaction mixt was cooled a t room temp, evapd to dryness, and dissolved in 40 ml of cold MeOH. This soln was allowed t o stand a t room temp for 16 hr and then was evapd to dryness. To the residue was added 20 ml of T H F and, after cooling, 20 ml of pH 4.R buffer. After standing 20 min a t room temp, T H F was removed i n z)ucuo, EtOAc was added to t,he residue, and the pH was adjusted t o 6.5 by addn of NaHC08. The org layer was dried (hIgS04) and evapd to give an oil. The cryst tosylate 4 mp 180-182", was obtd by mixing EtOAc solns of the amine and TsOH. tert-Butyl 3-Cyanomethyl-7-thiopheneacetamido-3-cephem-4carboxylate (5a).-To a stirred, cooled soln contg 467 mg (1.0 mmoles) of 4 suspended in 30 ml of IIeZCOwas added 420 mg ( 5 mmoles) of solid NaHC03,followed by 4x2 mg (3 mmoles) of thiopheneacetgl chloride. The reaction mixt was stirred in the cold for 1 hr and a t room temp for 3 h r ; the Me2CO was removed i n z)ucuo, and the residue was dissolved in C6H6. This soln was washed with cold 5% HCl, satd NaHC03, and satd NaC1, and was dried (XgSOa), evapd, and the residue was crystd from CC1, to give 418 mg, mp 164-166".
NOTES
3-Cyanomethyl-7-thiopheneacetamido-3-cephem-4-c~boxylic acid (5b).-A soln of 455 mg of ester 5a in 40 ml of 98-100% HC02H was stirred under NI for 2.5 hr a t room temp. The HCOzH was removed i n vacuo, and the residue was dissolved in EtOAc-NaHCOs. The layers were sepd, and a second extn was performed with a NaHC03 soln. The aq exts were cooled, layered with EtOAc, and adjusted to pH 2.8 wit,h 20y0 HCl. The org layer was washed with NaCl, dried (MgSO,), and evapd to give 234 mg of a golden foam. Crystn from Et20 gave 97 mg of acid 5 b , mp 114-117", characterized by spectral methods: uv, 268 mp (E 5400); ir (mull), c=o abs a t 5.57, 5.80, and 6.03 p . This material showed only 1 spot which was slightly faster moving than cephalothin on bioautogram (against Bacillus subtilis) in MEK-HzO (98:2).
Synthesis and Pharmacological Activity of Dialkylaminoalkyl Esters of Benzilic Acids
Containing Fluorine or Trifluoromethyl Groups I. LALEZARI,* AI. HATEFI, Department of Chemistry, Faculty of Pharmacy
11,A. KHOYI, N. GUITI,A N D F. ABTAHI Department of Experimental Medlcine and Phamnawlogy, Faculty of Aledicine, Unitersity of Tehran, Iran Receiced Youember 19, 1970
Continuing our studies on the synthesis of new potent local anesthetics,' and prompted by previous work on TABLE I
W
Yield. N o . Ri Rz
Ia F Ib F IC H Id F
H F H H
Ra
5%
H H CFa CFs
14
44 75
Mp, 'C 11C-1116 95-96
12
Bp (mm), OC Method 152-155 (5) A 17&180(15)c A 166-168(6 5) B 198-200 (753) B
Formulaa CirHiiFO CI~HIOF~O CisHiiFaO CiaHioFrO
All compds were analyzed for C, H, and the anal. values obtained were within iO.4g7, of the calcd figures. All compds were also subjected to ir and nmr spectroscopy and showed the expected absorptions. b A. Fisher, B. A . Grigor, J . Packer, and J. Vaughan, J . d m e r . Chem. Soc., 83, 4208 (1961), report mp 111'. W. Funasaka, T. Ando, H. Ozahi, and K. Murakami, Yuki Gosei Kngaku Kyokai Shi, 17,334 (1959) [Chem.Abstr., 5 3 , 17970 (1959)], report mp 96-97', bp 178-180" (15 mm). N. Sharghi and I. Lalezari, J . Chem. Eng. Data, 10, 196 (1965), report bp 166-168' (5.5 mm). a
TABLE I1
PJ Yield. No.
RI
R? H
Rs
?%
Mp, " C
Formula"
6.5 58-6ob CidHgFO: H F IIa ClaHgFz02 H 84 121-122' F F IIb 72 65 CijHsFsOn CFB H H IIc IId F H CF, 68 68-69 CL~HSF~OZ a See footnote a, Table I. b G. G. Smith and 0. Larson, J. Smith Amer. Chem. SOC.,82, 104 (1960), report mp 62-63'. and Larsorlb report mp 121.b122.5'. (1) N, Sharghi, I . Lalezan, G Xlloofari, and H. Golgolab, J. .Wed. Chem., 12, 696 (1969).
